The amount of lubricant oil should be controlled between upper and lower scale of oil dipstick. Overfull lubricant oil will get into the combustion chamber from the gap between cylinder and piston and form carbon deposits. The carbon deposits will increase the engine compression ratio and causes engine knocking. The carbon deposit easily leads to pre-ignition, if it falls into the cylinder, it will aggravate the friction and pollute the lubricant oil. Besides, overfull lubricant oil will increase the mixing resistance of crankshaft connecting rod and increase the fuel consumption.

This understanding is not comprehensive. For those lubricant oils without clean dispersant, it’s indeed that the oil has been a serious deterioration when it gets black; but for the lubricant oil for modern vehicles, which are generally with clean dispersant, will clean out the gum film and black carbon deposits attached to the piston, and disperse in the oil to reduce the sediment of the engine. Therefore, the oil will become black after a while, but it is not deteriorative.

It’s correct to check the lubricant oil frequently. But it will not make up the performance lost by only supply without changing it with the new one. During the process of lubricant oil is used, the pollution and oxidation will reduce the quality and quantity.

Truly premium lubricants are completed products with a variety of engine protection features; the formula has various additives including the anti-wear agent. And designing lubricant oil need to pay most attention to the balance of the formula to ensure the full play of various properties. Adding other additives casually will not result in additional protection to the vehicles; instead, cause the decline of overall performance of the engine oil due to the react with chemicals in the oil.